For many purposes motors are required having a small axial length and a large moment of inertia. This applies for example to record players, tape records and the like.
German patent specification No. 589,788 discloses an electric motor of this kind in which the winding, which has the appearance of a disk, is attached to the turntable of a record player and rotates with it, the iron of the turntable serving at the same time as part of the magnetic circuit. As a result of the relatively small mass of the winding, the rotor of such a motor possesses only a relatively small moment of inertia, and the bearing arrangement poses difficulties. In addition, the armature winding must be supplied with current by means of a collector. Furthermore, the manner in which the motor is mounted is not such as to inherently reduce the axial length of the motor, or expressed otherwise, is not inherently such as to reduce the space consumed by the mounted motor and the mounting means therefor, as considered in direction parallel to the rotation axis of the rotor of the motor.